New ELEV-8 and flight controller - what can it do???

W9GFO

I just dusted off my ELEV-8 with the intent of upgrading to a new flight control board. I see there is a new one offered by Parallax that looks interesting. The thing is, the ad copy is severely lacking. There is no mention of auto leveling, headless mode, altitude hold, position hold or ability to add GPS functionality - or any features that are programmed into it. Lots of detail about the board itself but pretty much nothing about what the board can do. If my only intent was to dive into quadcopter programming then the info is sufficient, but I want to know what it's capabilities are out of the box.

I had to download the manual and read to page 7 before there was any mention of auto leveling - and that's about all the info I could find on the flight controllers abilities.

Please inform me what this new board can do that the Hoverfly Sport could not. Then consider adding that information to the product page. ;-)

JasonDorie

At present there are 3 flight modes:

- Assist : auto level with altitude hold and ascent/descent rate control
- Stable : auto level only
- Manual : hold whatever orientation the user puts it in (basically a 3-axis heading hold gyro)

The auto-level modes let you set what the maximum flight angle is, and your stick directly controls the angle of the craft - centered is level. Manual mode has separate rate settings. The auto-level modes have a few extra stability assists in them, including tilt-compensated thrust and an accelerometer assist to help you hold a given height more easily.

The software supports S-BUS and PPM receivers in addition to normal PWM, so you can gain a lot of extra I/O pins and reduce wiring. There isn't a headless mode, GPS support, position hold, or a combined auto/manual mode, though these are all things that have been discussed and/or planned.

The firmware is still in active development, and the full source is available on GitHub.

I have a few flight demo videos on my YouTube channel if you want to see it in action, like this one (flight starts at about 1:12):

That quad doesn't have any vibration isolation between the board and body (which is standard on the Elev8 chassis) and all the settings are defaults, so it's a good indication of how the controller handles.

W9GFO

Thanks Jason, can you explain more about the tilt-compensated thrust feature?

JasonDorie

If the craft isn't perfectly horizontal, the thrust required to hold the current height (or rate of ascent/descent) is higher, because some of the thrust is being used to produce lateral movement, not lift. The thrust compensator calculates a scale factor to compensate for that. That value is scaled by a user setting that allows you adjust the effect (or disable it completely) and the result is used to scale the throttle to the motors.

There are limits - if you tilt too far it maxes out to prevent weird behaviors, but it helps quite a bit.

DavidZemon

JasonDorie wrote: »

If the craft isn't perfectly horizontal, the thrust required to hold the current height (or rate of ascent/descent) is higher, because some of the thrust is being used to produce lateral movement, not lift. The thrust compensator calculates a scale factor to compensate for that. That value is scaled by a user setting that allows you adjust the effect (or disable it completely) and the result is used to scale the throttle to the motors.

There are limits - if you tilt too far it maxes out to prevent weird behaviors, but it helps quite a bit.

Well done. I have a little $40 quad that I fly around in the house, and the fact that it is missing this feature bothers me to no end. Glad you implemented it on the Elev8!

JasonDorie

I assumed that new pilots would find it easier to fly with that in place, and people who had helicopter experience might find it obnoxious, because muscle memory will do that for you after a while, so it can be adjusted. I personally like it - it means I can often fly with just one hand while filming with the other.

Publison

JasonDorie wrote: »

At present there are 3 flight modes:

- Assist : auto level with altitude hold and ascent/descent rate control
- Stable : auto level only
- Manual : hold whatever orientation the user puts it in (basically a 3-axis heading hold gyro)

Will the mode select move off of the Gear switch, and go to a 3-4 position switch on the transmitter?

JasonDorie

Any function can be assigned to any of the 8 input channels in GroundStation, so if you want to move the Mode switch it's easy to do, but I won't likely change the default for that. With an S-BUS or PPM receiver you have access to 16 channels from the code, I just don't expose them to the GroundStation settings, but I easily could - the firmware would just work.

If I add more modes I'll have to figure out how best to choose them. I might leave it as a 3-pos and let you pick which 3 to choose from, or let you assign ranges on the mode channel, so if your radio can do 4 we'll let you.

Publison

JasonDorie wrote: »

Any function can be assigned to any of the 8 input channels in GroundStation, so if you want to move the Mode switch it's easy to do, but I won't likely change the default for that. With an S-BUS or PPM receiver you have access to 16 channels from the code, I just don't expose them to the GroundStation settings, but I easily could - the firmware would just work.

If I add more modes I'll have to figure out how best to choose them. I might leave it as a 3-pos and let you pick which 3 to choose from, or let you assign ranges on the mode channel, so if your radio can do 4 we'll let you.

OK. I was just relating to the Running Lights Upgrade on Learn:
http://learn.parallax.com/print/book/export/html/1245

Matt refers to four modes with the running lights, not sure how to access that.

xanadu

I would do the customizable PWM signal range in the FC software. That would be a nice addition.

Publison I'm not sure if this is what you meant but you can use a mix and another switch. I have 6 flight modes using two switches. One is a three position and one is a two position.

Sw1 / Sw2 / mode

pos1+pos1 = mode 1 stability
pos1+pos2 = mode 2 rattitude
pos2+pos1 = mode 3 rate
pos2+pos2 = mode 4 rate w/ negative expo
pos3+pos1 = mode 5 rattitude w/ cruise control
pos3+pos2 = mode 6 stability

I can mash both switches either direction to get into stability. I had to setup voice alerts as reminders as to what mode I'm in. Confusing rattitude with attitude can be incredibly expensive.

I will need to add "Skywriter" mode soon. I'm waiting for Carol to get her copter

JasonDorie

Keep reading - that page includes the modifications to the firmware required to run the lights and switch between modes. I think he does it by holding the sticks in a set direction when landed, but it could easily be done with an unused radio channel.

bosephe

In videos of the ELEV-8 V3 does not seem to be as stable as the video of the phantom with the Parallax flight controller.

Does the parallax flight controller have difficulty controlling larger/heavier drones.

In one of the video demonstrating altitude hold it was said that the altitude could vary +/- 3 feet. Is that accurate or has the performance been improved?

Since the flight controller hardware has support for up to 6 ESCs does that mean the firmware support hexacopter configurations.
There is a video on youtube of a Elev-8 v3 hexacopter so will the parallax FC work with other hexacopter platforms.

JasonDorie

The phantom body shell is very small and light, and responds a faster to commands because of it. This is normal. I also don't tend to tune the controller because I reset / reflash so often. The settings can be tuned to tighten the control up some.

For altitude control, the hold height is probably within about 2 feet now, but that's due to the barometer - air pressure varies, so the altitude will vary with it. If you use an absolute ground height sensor like the laser rangefinder, hold height is within a few mm.

Hex support is added to the latest (unreleased) version of the software, and will be included in the public version relatively soon. You're likely seeing Matt testing it. The flight controller can technically handle many more than 6 ESCs with a bit of user code, but the firmware as delivered supports only quad or hex configs.